PAX East 2011: First look at Portal 2's opening scenes

Later, we spoke toProject LeadJoshua Weier for some insight on Portal 2's story and characters. We first asked Weier about the development of Portal 2's new characters, such as Wheatly and Johnson, and whether or not we'll find out more about Chell herself.

"Chell has always sort of been an avatar for the player, so initially we weren't going to use Chell - we were going to use a new character, but people said time and time again that it was weird that 'GLaDOS didn't know who I was.' They didn't mean Chell per se, they meant 'me as a player,' like, 'I had this experience with GLaDOS and now she doesn't know who I am.' So it was important to keep Chell for that reason," said Weier.

"But really Chell is just sort of a personification of the player in the game. But with characters like Wheatly, Cave Johnson, and GLaDOS, they refer to you as the player, and I think it's important to draw the player into the game - feeling like you're really there."

Apparently, Chell wasn't the only element of Portal that Valve considered replacing - Weier told us that early ideas entirely replaced the portal gun with a new device, which Valve worked on before deciding to stick with the portal mechanic and add new elements - like the Repulsion Gel - to change up the puzzles. But that doesn't mean the idea was scrapped forever - Valve isn't ready to spill any of its Portal 2 prototyping work.

"We're still kicking that around - it's kind of interesting. I think that kind of came from us trying to make Portal 2 surprise. But the more we started to dig into the mechanics, the more we realized there was tons more for us to do," said Weier.

Back on the subject of Portal 2's characters, we asked Weier about Valve's decision to cast J.K. Simmons as Aperture founder Cave Johnson. He revealed that Simmons was the only actor Valve considered:

"We got thinking like, 'who's the person who should be this character,' and it was always J.K. Simmons, and he was interested in doing it. I think he's the only voice actor who ever wrote us a 'thank you' letter afterwards. So he was the most gracious guy - it was awesome."

Weier wouldn't comment on whether or not Johnson, whose only presence in what we saw came as a pre-recorded voice, was still alive, saying that he doesn't "want to reveal any spoilers." Weier did explain that the facility we saw was "older Aperture" - presumably before GLaDOS. Speaking of spoilers, Weier also wouldn't comment on the leaked Achievements - and any Half-Life teasers within - though he did verify that they were legitimate.